This invention relates to a machine and method that may be used for applying a non-destructive test to a package such as a vacuum package, containing, for example, food, chemicals or medicines. This may be to check that the sealing of the package is good, e.g. so that the product within the package cannot escape from the package; nor can the outside atmosphere enter the package. It is particularly applicable to packages having flexible outer layers of plastics films.
A machine of such type is useful, for example, in production lines, where it would be desirable to verify the integrity of the seals of the complete production throughput without destroying the packages or products.